NFSv4.1: pnfs: full mount/umount infrastructure

Allow a module implementing a layout type to register, and
have its mount/umount routines called for filesystems that
the server declares support it.

Signed-off-by: Fred Isaman <iisaman@netapp.com>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Andy Adamson<andros@netapp.com>
Signed-off-by: Bian Naimeng <biannm@cn.fujitsu.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

3 files changed, 101 insertions, 4 deletions

diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 3f69752d6f18..d94311943ec6 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -75,13 +75,17 @@ config NFS_V4
 
 config NFS_V4_1
 	bool "NFS client support for NFSv4.1 (EXPERIMENTAL)"
-	depends on NFS_V4 && EXPERIMENTAL
+	depends on NFS_FS && NFS_V4 && EXPERIMENTAL
+	select PNFS_FILE_LAYOUT
 	help
 	  This option enables support for minor version 1 of the NFSv4 protocol
-	  (draft-ietf-nfsv4-minorversion1) in the kernel's NFS client.
+	  (RFC 5661) in the kernel's NFS client.
 
 	  If unsure, say N.
 
+config PNFS_FILE_LAYOUT
+	tristate
+
 config ROOT_NFS
 	bool "Root file system on NFS"
 	depends on NFS_FS=y && IP_PNP
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index b483026e82aa..cf795625610e 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -32,16 +32,51 @@
 
 #define NFSDBG_FACILITY		NFSDBG_PNFS
 
-/* STUB that returns the equivalent of "no module found" */
+/* Locking:
+ *
+ * pnfs_spinlock:
+ *      protects pnfs_modules_tbl.
+ */
+static DEFINE_SPINLOCK(pnfs_spinlock);
+
+/*
+ * pnfs_modules_tbl holds all pnfs modules
+ */
+static LIST_HEAD(pnfs_modules_tbl);
+
+/* Return the registered pnfs layout driver module matching given id */
+static struct pnfs_layoutdriver_type *
+find_pnfs_driver_locked(u32 id)
+{
+	struct pnfs_layoutdriver_type *local;
+
+	list_for_each_entry(local, &pnfs_modules_tbl, pnfs_tblid)
+		if (local->id == id)
+			goto out;
+	local = NULL;
+out:
+	dprintk("%s: Searching for id %u, found %p\n", __func__, id, local);
+	return local;
+}
+
 static struct pnfs_layoutdriver_type *
 find_pnfs_driver(u32 id)
 {
-	return NULL;
+	struct pnfs_layoutdriver_type *local;
+
+	spin_lock(&pnfs_spinlock);
+	local = find_pnfs_driver_locked(id);
+	spin_unlock(&pnfs_spinlock);
+	return local;
 }
 
 void
 unset_pnfs_layoutdriver(struct nfs_server *nfss)
 {
+	if (nfss->pnfs_curr_ld) {
+		nfss->pnfs_curr_ld->uninitialize_mountpoint(nfss);
+		module_put(nfss->pnfs_curr_ld->owner);
+	}
 	nfss->pnfs_curr_ld = NULL;
 }
 
@@ -74,7 +109,18 @@ set_pnfs_layoutdriver(struct nfs_server *server, u32 id)
 			goto out_no_driver;
 		}
 	}
+	if (!try_module_get(ld_type->owner)) {
+		dprintk("%s: Could not grab reference on module\n", __func__);
+		goto out_no_driver;
+	}
 	server->pnfs_curr_ld = ld_type;
+	if (ld_type->initialize_mountpoint(server)) {
+		printk(KERN_ERR
+		       "%s: Error initializing mount point for layout driver %u.\n",
+		       __func__, id);
+		module_put(ld_type->owner);
+		goto out_no_driver;
+	}
 	dprintk("%s: pNFS module for %u set\n", __func__, id);
 	return;
 
@@ -82,3 +128,41 @@ out_no_driver:
 	dprintk("%s: Using NFSv4 I/O\n", __func__);
 	server->pnfs_curr_ld = NULL;
 }
+
+int
+pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+	int status = -EINVAL;
+	struct pnfs_layoutdriver_type *tmp;
+
+	if (ld_type->id == 0) {
+		printk(KERN_ERR "%s id 0 is reserved\n", __func__);
+		return status;
+	}
+
+	spin_lock(&pnfs_spinlock);
+	tmp = find_pnfs_driver_locked(ld_type->id);
+	if (!tmp) {
+		list_add(&ld_type->pnfs_tblid, &pnfs_modules_tbl);
+		status = 0;
+		dprintk("%s Registering id:%u name:%s\n", __func__, ld_type->id,
+			ld_type->name);
+	} else {
+		printk(KERN_ERR "%s Module with id %d already loaded!\n",
+			__func__, ld_type->id);
+	}
+	spin_unlock(&pnfs_spinlock);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(pnfs_register_layoutdriver);
+
+void
+pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
+{
+	dprintk("%s Deregistering id:%u\n", __func__, ld_type->id);
+	spin_lock(&pnfs_spinlock);
+	list_del(&ld_type->pnfs_tblid);
+	spin_unlock(&pnfs_spinlock);
+}
+EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index c628ef131d83..61531f338576 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -36,8 +36,17 @@
 
 /* Per-layout driver specific registration structure */
 struct pnfs_layoutdriver_type {
+	struct list_head pnfs_tblid;
+	const u32 id;
+	const char *name;
+	struct module *owner;
+	int (*initialize_mountpoint) (struct nfs_server *);
+	int (*uninitialize_mountpoint) (struct nfs_server *);
 };
 
+extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *);
+extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *);
+
 void set_pnfs_layoutdriver(struct nfs_server *, u32 id);
 void unset_pnfs_layoutdriver(struct nfs_server *);